In the course of the codetermination debate of the 2000s, managers of large companies surprisingly made codetermination-friendly statements by claiming to disagree with employer federation demands to reduce the number of employee seats on supervisory boards from one half to one third. This claim can be interpreted in two different ways.According to the power resource interpretation, managers hesitated to publically articulate their aversion to codetermination so as not to undermine cooperation with the employee representatives in their own companies. In contrast, the production regime interpretation assumes that managers really had changed their basic preferences. We compare the attitudes of managers and federations in the 1970s and the 2000s and show that the power resource interpretation cannot be upheld. The key to understanding the diverging attitudes between managers and federations in the 2000s does not lie in the supposed opportunism of managers, but in the uncertainty of the effects of institutional change.